According to the City of Västerås, the marina in Västerås is Sweden's largest marina with just over 3,400 berths for leisure boats.
During the summer, activity increases on the lake and the surrounding islands, which leads to more crimes according to the police.
In recent years, bus driving with jet skis has become an increasingly common problem.
- People have bought or rented jet skis that they do not master and you drive in a very disruptive way near ports and bathing places.
There are national problems that exist around big cities, but it is something we have seen here in Västerås as well, says Mattias Olander.
Hear the police tell you more about the new venture in the clip.